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usb: hub: try old enumeration scheme first for high speed devices 

The new scheme is required just to support legacy low and full-speed
devices. For high speed devices, it will slower the enumeration speed.
So in this patch we try the "old" enumeration scheme first for high speed
devices, and this is what Windows does since Windows 8.

Signed-off-by: Zeng Tao <prime.zeng@hisilicon.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Reviewed-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Zeng Tao 2018-09-28 19:27:52 +08:00 committed by Greg Kroah-Hartman
parent 2cfe8f864d
commit bd0e6c9614
2 changed files with 5 additions and 2 deletions
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3
Documentation/admin-guide/kernel-parameters.txt
View File

@ -4610,7 +4610,8 @@
usbcore.old_scheme_first=
[USB] Start with the old device initialization
scheme (default 0 = off).
scheme, applies only to low and full-speed devices
(default 0 = off).
usbcore.usbfs_memory_mb=
[USB] Memory limit (in MB) for buffers allocated by

4
drivers/usb/core/hub.c
View File

@ -2661,11 +2661,13 @@ static bool use_new_scheme(struct usb_device *udev, int retry,
{
int old_scheme_first_port =
port_dev->quirks & USB_PORT_QUIRK_OLD_SCHEME;
int quick_enumeration = (udev->speed == USB_SPEED_HIGH);
if (udev->speed >= USB_SPEED_SUPER)
return false;
return USE_NEW_SCHEME(retry, old_scheme_first_port || old_scheme_first);
return USE_NEW_SCHEME(retry, old_scheme_first_port || old_scheme_first
|| quick_enumeration);
}
/* Is a USB 3.0 port in the Inactive or Compliance Mode state?